This invention relates hinged vehicle safety devices and more particularly to actuators for hinged vehicle safety devices.
U.S. Pat. No. 5,357,239 granted to Ronald C. Lamparter Oct. 18, 1994 discloses an actuating device for operating a safety unit, such as a crossing arm or a stop sign, that moves between a retracted position adjacent the vehicle and an extended position extending outwardly from the vehicle. A housing is mounted on the vehicle and a bracket is pivotally mounted on the housing for movement about a vertical pivot axis between a retracted position and an extended position. The actuating device includes a drive mechanism having a drive unit for pivoting the bracket about the pivot axis and an electric motor for driving the drive unit.
U.S. Pat. No. 5,719,553 granted to Ronald C. Lamparter Feb. 17, 1998 discloses a sealed actuator assembly for hinged vehicle safety devices, such as a crossing arm or a stop sign. The sealed actuator assembly is attached to the vehicle and includes the electrical and mechanical components that pivot the hinged safety device from a stored position adjacent the bus to an operative position extending outwardly of the bus. These components and wiring harnesses are protected in an outer sealed housing that has a removable cover to facilitate installation and repair. Installation and repair is further enhanced by a removable inner housing sub-assembly that carries a motor control circuit for the electric motor and provides additional protection for the electric motor.
The actuators described above are very satisfactory for their intended purpose. However, both actuators use an electric motor to pivot the vehicle safety device, which is fine because all vehicles include an electric storage battery for a power source. On the other hand, some vehicles and school busses in particular, normally include a fluid power source such as an air pump for operating other systems and accessories. The fluid power source may be preferred over the electrical power source for one reason or another. However, the fluid power source cannot operate the actuators described above.
Consequently, an actuator assembly for hinged vehicle safety devices, such as a fluid actuator assembly for hinged vehicle safety devise has been developed by Transpec, Inc., the assignee of the invention which is the subject of this patent application. The fluid actuator assembly, which is disclosed in pending U.S. patent application Ser. No. 09/798,149, now U.S. Pat. No., 6,435,075, issued Aug. 20, 2002 has a housing with a fluid motor attached inside the housing. A lever arm is pivotally attached to the housing for pivotal movement by the fluid motor between retracted and extended positions. A rotor is rotationally mounted in the housing for movement between retracted and extended positions, the rotor having a spool at one end and an eccentric arm next to the spool that engages the lever arm. A torsion spring encircles the spool with one end engaging the rotor and an opposite end engaging a stop in the housing so that the eccentric arm is biased against the lever arm and the rotor and the lever arm are biased to their respective retracted positions. When pressurized fluid is admitted into the fluid motor, the fluid motor pivots the lever arm toward the extended position. The lever arm in turn rotates the rotor and the safety device attached to it toward the extended position.
The rotor preferably has a spool and a torsion spring at each end for balanced operation. The housing preferably has a base and a removable cover while several internal parts preferably form a sub-assembly to make assembly easier.
The fluid actuator assembly that Transpec, Inc. developed, is satisfactory for its intended purpose. However, the fluid actuator can be improved, particularly with regard to facilitating assembly of the rotor and torsion springs.
The fluid actuator assembly of this invention has a rotor unit that includes the torsion spring or springs, each of which are held in a preloaded condition by a preload spring clip. This rotor unit or sub-assembly results in an improved assembly process that is easier that the assembly process of the fluid actuator assembly described in the ""149 patent application.